Method of making building panels



Oct. 20, 1953 B. ROENSCH EI'AL mamen OF MAKING BUILDING PANELS 4 Sheets-Sheet l Filed May 1, 1947 ////////////////Lj/////////////////// //////V////w//////// A/////////// NvENToRa 20646504 40 3 44 PM &oa-'vai: %4:1 GM

ATTORNEYS Oct. 20, 1953 B. ROENSCH ETAL ME'I'HOD OF MAKING BUILDING PANELS Filed May 1, 1947 4 Sheets-Sheet 2 Oct. 20, 1953 B. RoENsc- ETAL METHOD OF MAKING BUILDING PANELS Filed May l. 1947 4 Sheets-Sheet 3 NVENTORS ,am W

ATTONEYS Oct. 20, 1953 B. ROENSCH arm METHOD OF( MAKING BUILDING PANELS 4 Sheets-Sheet 4 Filed May l. 1947 !NVENTORS 34% %M ?od BY WM gp ATTORNEYS Patented Oct. 20, 1953 4 2,655,7 o ME'rnon OF MAKING BUILDING mms Burns Roensch, Houston, Tex., and Paul Brown.

New York, N. Y., assignors, by mesne assignments, to Daystrom. Incorporated, a corpora- I tion of New Jersey Application May 1, 1947, Serial No. "5,332

of large precast panels having.over-all dimen sions of approximately 4 feet by feet -with a thickness of 4 to 8 inches. the complete panel being preferably a hollow wall structure comprising two reinforced slabs of concrete Joined by metal reinforcing members embedded in each slab.

In the manufactu're of large precast building panels. it is essential to have not only adequate strength in the panel structure but also a smooth,

durable, hard surface free from unsightly cracks and blemishes.

In the manufacture of precast building panels Q it has been proposed heretofore to employ suction or vacuum molds and to pour the concrete into these'molds. whereupon a, high vacuum is applied to the concrete. through a fine filter screen whereby excess water is removed from the concrete. This vacuum treatment draws some of the fine particles of cement to the filter screen and this cement frequently adheres to the screen with such tenacity that when the molded slab is separated from the screen, patches of cement adhere to the screen with the result that the finished slab has unsightly spots or areas which have'to be retouched by manual Operations.

After repeated experiments with this method of producing precast slabs. it was discovered that the dimculties encountered in separating the slab from the vacuum mold were due in large measure to the high density of the fine layer of cement formed at the surface adjacent the filter screen. It was found that these difficulties could be surmounted by diluting this 'surface layer of fine cement,and the best method of accomplishing this result was found to be the use of a fabric. preferably a woven fabric, such as cheesecloth or the like. By placing this fabric in the mold adiacent thesuction surface or surfaces thereof, prior to pouring the concrete in the mold, it was found that the subsequent vacuum treatment caused fine particles of cement to form a surface layer adjacent the filter screen with the fabric permanently embedded in this layer of -flne cement. The fabric thus became a permanent part 9 Claims. (oi. -15!) of thecastpanelanditservedthep moseof diluting the fine cement layer to an extent such that it would not adhe'e to the filter screen. It was thus found to be possible to form slabs of large dimensions having a perfect surface free from blemishes. It was also fomd that the fabric embedded in the surface of the slab eliminated the tendency for the surface layer to crack or craze.

It has also been proposed heretofore to form precast concrete panels by placing a sheet of any suitable liner material in the bottom of a mold and then pouring concrete into the mold and allowing the concrete to set before removing the slab from the mold. In making panels in this manner, several hours must elapse before the slab can be removed from the mold and the surface liner is not an integral part of the slab as is the case where a vacuum treatment is applied as in our invention which results in the fabric being completely and permanently embedded in the surface of the slab. By employing our invention it is possible to remove the panel from the mold within a few minutes after the concrete is poured and as explained above. the use of a fabric which becomes permanently embedded in the surface of the slab adjacent the filter screen of the mold, prevents sticking of the concrete to the mold when the slab is removed.

In general, one embodiment of our improved .process involves placing a sheet of fabric over the filter screen of a suction mold. pouriug a wet mixture of cement and aggregate into the mold in contact with the fabric lining the bottom of the mold; applying a vacuum through the bottom of the mold to withdraw surface water through the fabric and through the filter screen while the top surface of the concrete is exposed to the atmosphere, this vacuum treatment being continued until the, concrete forms a coherent solid panel, and then removing the panel from the mold. The total time required for making a single wall panel need not be greater than ten to flfteen minutes because within this time all excess water has been removed from the panel and it is hard enough to handle without danger of injuring any portion of the concrete slab. After removing the slab from the mold, it may be placed on a suitable support and allowed to stand for several hours to where the mold l occupies a a 3 can then be discontinued and the Panel lifted awa from the upright mold. In some instances it is preferable to invert the mold by turning it through an angle of 180 while continuing the vacuum treatment. The mold is then-lifted from the panel after shutting otr the vacuum.

In making a double wall panel according to our improved process, two complementary molds are employed. concrete is first poured into one mold preferably containing a liner sheet of fabric. A unitary metal 'cage reinforcing structure is inserted in the mold until a portion of this structure is embedded in the soft concrete, the vacuum is applied to withdraw water concrete until it forms a coherent mass with the metal cage partially embedded therein. and then concrete is poured into the second mold and the first mold inverted over the second mold. The two molds are then brought close together so that the metal reinforcing structure partially embedded in the slab formed in the first mold is forced into the soft concrete mass in the second mold, and then. with the two 'mold sections thus superimposed. vacuum is applied'to the second mold to form the concrete poured thei-ein into a coherent mass. The first mold can then be lifted and turned back to its initial position, and then the second mold can; be raised to a vertical position. or inverted, to faoilitate removal of the completed double wall slab from the second mold.

The various objects and advantages of our invention will be more apparent from the !ollowing detailed description of typical embodiments thereof iliustrated in the accompanying drawings in which: i

Fig. 1 is a perspective view partly in section showing a finished double wall building panel embodying our invention:

Fig. 2 is a pers ective view ot a form of unitary metal reinforcing cage suitable tor use in accordance with our invention:

Fig. 3 is a perspective 'view of apparatus illustrated in diagrammatic form, suitable for performing my improved process;

Figs. 4-8, inclusive, are diagrammatic views of the apparatus illustrated'in Fig. 3 showing the series of Operations performed in making a double wall panel in accordance with our invention;

and A Fig. 9 is an enlarged perspective view of a' illustrated panel removing device.

Referring first to the apparatus as in Figs. 3-8, inciusive. we have shown in diagrammatic form a pair of comnlementary molds i and 2. Each mold has a bottom suction surface covered with one or more superimposed filter screens 3 and side walla 4. Ducts li and i communicate with the bottom of mold I and with a hollow tubular duct 1 connected to a vacuum pipe 8 leading to a vacuum pump (not illustrated).

The tubular duet 'I of mold I is rigidly connected to the framework s of the mold' and the ends of this tube are iournalled in bearings II Hydraulic cylinders I! and !3 are connected to a erank member ll fixed to the duet the suply of fluid to the and s. the duet 1 and the mold I rigidly connected thereto can be rotated through approximately 180, i. e., from the position shown in Fig. 3 to the position shown in 4-6. inclusive, potion directly above the mold 2. oorresponding hydrauli cylinfr'om the mass of 4 ders IS and IS connected to acrank member Il fixed to the duet 'l at a point near the vacuum connection I may be operated in unison with the hydraulic cylinders !2 and I: to rotate the mold l from one position to another as desired. The hydraulic cylinders I: and iS are carried by supports i! and I! and the cylinders I: and IC are connected by supports and z. Brackets 22 and 23 carry adjustable supporting studs 24 and !I adapted to support the free end of the mold I when it occupies the position shown in Fig. 3.

. The mold 2 is rigidly connected to a hollow tubular duet member 26 which communicates with the bottom of this mold through its ducts 5 andi, and with vacuum connection 21. The duet 26 is Journalled in vertical adjustable bearings 28 and 29 and hydraulic cylinders :0 and !I can be operated in unison to rotate the mold 2 about the axis of the duet 25. Hydraulic lifting jacks 32, 33. 34 and 35 are provided to 'raise and lower the mold 2 in the manner and for the purpose hereinafter described.

It will be underood that the apparatus diagrammatically shown in the accompanying draw ines is disclosed in this application soiely for the purpose oi' iilu'strating apparatus suitable for making the improved concrete pane in accordance with the improved panel-making process of this invention. i

In utilizing apparatus such as that shown in Figs. 3-8 of the accompanyi drawings; a sheet of woven fabric 38 may be placed in the mold I. this sheet of fabric being large enough to cover the b'ottom oi' the mold and to cover the side walls or edges 4 of the mold. This fabric Ci is preferably woven tabric such as cheesecloth, the i'abric being preferably sized to make it somewhat stifi and !ree from wrinJkes which might mar the appearance of the surface ot the finished panel. The use of a cloth fabric is advantageous because oi' its characteristic of shrinking to some extent when wet, and accordingly any tendency of the fabric to form wrinkles is eiminated by the shrinldng action which occurs when the wet concrete mixture is poured into the mold.

After the iabric 35 has been placed in the mold i as described above, a very wet mixture of cement aggregate and water is poured into this mold until it substantially lls the mold. This mass of concrete is shown at 31 in Figs. 3-8, inclusive. A typical concrete mixture found to be suitable for the. purposes ot this invention consists of coarse and fine foam slag aggregate in the proportions of one part by volume of coarse slag for each three parts oi fine slag. and

for each bag of cement (94 pounds) approximately 11% gallons of water are used. For each 1.6 cu. tt. of cement we prefer to use approximately 8.2 cu. ft. of the mixture of coarse and fine tom slag. It will be understood that other concrete mixtu'es may be employed and I that the proportions herein set forth are merely verywetmixtm'esothat given as an llustrative example of a mixturr found to be entirely satisfactory. This 'mixture contains more water than is ordinarly used in mixing concrete, but it is desirable to have a it readiiy fllls the vacuum mold and so that it is soft enough to receive the metal reinforcing cage. w

As soon as the batch of concrete is poured into the mold .I as explained above. and leveled off in this mold, even with the top of the mold, the unitary reinforcing cage structure best illustrated in Flas. 1 and 2, is lowered into the mold until 4 5 a portion of this cage 'is embedded in the soft mass of concrete: As illustrated in Figs. 1 and 2. this unitary metallic reinforcing cage* consists of a rectangular frame' comprising side studs 38 and 39 welded or otherwise rigidly fixed to end studs 40 and 4l. and each face of this !rame is covered by a wire mesh 42 welded or otherwise rigidly, fixed to the side and end stud sections 38, 39, 40 and 4l. The side and end studsare preferably-metal channel sections having marsinal flanges as shown at 43 in Fig. 1 connected by a web having cut out po'rtions as best illustrated at44inFigs.1and2.

After the metal cage has been lowered into the soft concrete mass in mold kthe vacuum is applied to the bottom. of this mold by opening a valve or valves in the vacuum line connecting the vacuum pump with the duct member 'I communicating with the channels 5 and 6. A vacuum of approximately 18 inches of mercury is applied for several minutes, during which time all excess water in the batch of concrete ,in the mold I is withdrawn through the fabric 33 and through the filter screen or screens 3 in the bottom of this mold and the concrete in this brief period* of time, solidifles to such an extent that it forms a coherent body. As this vacuum treatment is continued, the mold I is rotated to an angle of approximately 90 to an upright position and while this operation is being performed, a second batch of concrete is poured into the mold 2. onto a'layer of fabric 35 covering the bottom and side walls of this mold 2. The first mold I is then rotated further until the panel therein with the metal cage projecting therefrom is directly above the second mold as best illustrated in Fig. 4. It will be understood that this inversion of mold l is accomplished by manipulating valves supplying fluid to the hydraulic cylinders z, !3, l5 and it, while continuing the application of the vacuum to the mold I.

With the apparatus in the position illustrated in Fig. 4, the hydraulic jacks 32. 33. 34 and 35 are operated to lift the second mold 2 until the metal cage carried by the solidified panel in the first mold becomes partially embedded in the soft mass of concrete in the second mold. the position of the parts being then as illustrated in Fig. 5. The vacuum is then applied to the mass of concrete in the second mold mtiLthe excess water is withdrawn from this mass through the layer of fabric in this mold.

While this vacuum treatment is being carried out and-after the concrete 31 in the second mold has formed a coherent body. the hydraulic jacks 32, 33, 34 and 35 may be manipulated to lower the second mold, thus separating the molded panel body from the first moldsection I as best illustrated in Fig. 6. The first mold section can then be rotated back to its initial position as illustrated in Fig. 7 and then, while continuing the vacuum treatment of the concrete in the second mold 2, this mold may be rotated into an upright position as best illustrated in Fig. 8. The vacuum may then be shut off' and the finished panel may be lifted from the mold section 2 by any suitable mechanism engaging the metal stud elements, either at the ends of the panel or at the bottom edge 'of the panel, so that the lifting force is applied to the metal reinforcing cage. If desired, however, the second mold 2 may be completely inverted before the panel is separated therefrom. in which event the vacuum is continued until the complete Inversion has taken place and the panel is brought to rest on a suittion shown in Figs. 3-7, inclusive.

The remo'val oi' the finished panel from the mold 2 while this mold occupi'es an upright position as illustrated in Fig. 8, can be accomplished by placing an I-beam or the like 45 along the bottom of a panel and in contact with the metal reinforcing cage. With the panel thus supported along its bottom edge by this I-beam, the panel and mold can be separated from each other and the mold section 2 then rotated back into a horizontal position.

As stated above, satisfactory results can be obtained by employing a vacuum of approximately 18 inches of mercury. It is to be understood, however, that a vacuum ranging from approximately 8 inches of mercury to 24 inches of mercury may be employed as desired, the higher the vacu'm the shorter the time required for tvithdrawing the excess water from the concre The product here disclosed having a sheet! of reinforcing fabric or the like permanently embedded in one or both exposed surfaces is fully disclosed and claimed in our copending application Ser. No. 307542, filed September 3, 1952.

It will also be understood that in some instances it may not be necessary to employ a reinforcing sheet of fabric or the like permanently embedded in one or both exposed surfaces of the precast panel and therefore according to one embodiment of our improved process, the fabric can be dispensed with and the panel formed by pouring the concrete directly onto the filter screen in the bottom of the mold, the subsequent Operations then being performed as described above. Claims directed to the process without employment of the fabric' and claims to the apparatus here disclosed are contained in co-pending application Serial No. 75,416 of Burns Roensch. filed February 9. 1949.

various changes in the process and product as described above can be made within the scope of the'appended claims.

We claim:

1. The process of making a reinforced concrete building panel which comprises placing a sheet of reinforcing fabric in a mold having a suction surface, pouring concrete into the mold in contact with said fabric, applying a vacuum to the concrete through said surface of the mold with a surface of the concrete exposed to the atmosphere, whereby water and fine particles of cement are drawn from the concrete through said fabric to embed the same in a layer of cement, and separating the panel from the mold with the fabric permanently embedded in one surface of the panel.

2. The process of making a reinforced concrete building panel which comprises placing a sheet of reinforcing fabric in a mold on a suction surface thei-cof, pouring concrete into the mold in contact with said fabric, applying a vacuum to the concrete through said surface of the mold with a surface of ,the concrete exposed to the atmosphere whereby water and fine particles of fabric permanently embedded in one surface of the panel.

3. The process of making a precast reinforced concrete building panel which comprises placing in a horizontal position a mold having a suction surface. placing a sheet of reinforcing fabric in the mold, pouring concrete into the^mold over said fabric and immediately applying a vacuum to the concrete through said suction surface with a surface of the concrete exposed to the atmosphere whereby water and fine particles of cement entrained therein are drawn from the mass of concrete through said fabric whereby the fabric is embedded in a layer of cement thus drawn to the surface of the mass, continuing the vacuum treatment until suilicient water has been removed from the concrete mass to cause the' same to form a coherent solid panel. and then discontinuing the vacuum and immediately separating the panel from the mold with the fabric permanently embedded in a. surface of the panel.

4. The process of making a 'precast reinforced concrete building panel which comprises providing a mold having a horizontal suction surface, placing a sheet of reinforcing fabric in the mold over said surface, pouring a mixture of cement, coarse and fine aggregate and water into the mold in contact with the fabric and immediately applying a vacuum to the mixture through said suction surface with a surface of the mixture exposed to the atmosphere whereby water is drawn from the mixture through said fabric so' that cement particles and fine aggregate. entrained in'this water form a surface layer of cement and fine aggregate at the bottom of the mixture with the fabric embedded in this layer, continuing the vacuum treatment until suflicient water-v has been withdrawn from the mixture to cause the mass to form a coherent solid panel and then discontinuing the vacuum treatment and removing the panel from the mold with the fabric permanently embedded in one surface of the panel.

i 5. The process of making a precast reinforced concrete building panel which comprises providing a mold having a horizontal suction surface, placing a sheet of reinforcing fabric in the mold over said surface, pouring a mixture of cement, coarse and fine aggregate and water into the mold in contact with the fabric and immediately applying a vacuum to the mixture through said suction surface to draw water from the mixture through said fabric whereby cement particles and fine aggregate entrained in this water form a surface layer of cement and fine aggregate at the bottom of the mixture with the fabric permane tly embedded in this layer, turn- Sng the mold through an angle of approximately 90 until the panel is in a substantially vertical position while continuing the vacuum treatment, then discontinuing the vacuum treatment and separating the panel from the mold.

6. The process of making-a precast reinforced concrete building panel which comprises placing a mold having a suction surface with said surface in a horizontal position; placing a sheet of reinforcing fabric in the mold Von said surface. pouring concrete into the mold. inserting a unitary metal reinforcing structure in the mass of concrete with portions of this structure projecting above' the mass of concrete, applying a vacuum to the concrete through said suction surface to draw water from the concrete through the reinforcing fabric whereby cement particles entrained in this water rom a surface layer of cement at the bottom of the mass with the fabric embedded in thislayeof cement, continuin the vacuum treatment until the concrete forms a coherent solid panel, inverting the mold while continuing to apply t e vacuum to the concrete mass, andthen discontlnuing the vacuum treatment and separating the panel from the mold with the fabric permanently embedded in the layer of cement,

7. The process of making arprecast reinforced concrete building panel which comprises placing a mold having'a suction surface with said surface in a horizontal position. placing a sheet of reinforcing fabric in the mold over said surface, pouring concrete into the mold in contact with said fabric, inserting a unitary metal reinforcing structure into the concrete mass with portions of said structure projecting above the surface of the mass, applying a vacuum to the concrete mass through said vacuum surface and through the fabric to exhaust water from the mass and to embed the fabric in a layer of cement drawn to the surface of the mass by the vacuum treatment, placing a second mold having a suction surface with said 'surface in a horizontal position and pouring a second mass of concrete into the second mold, inverting the first mold over the second mold while continuing the application of vacuum to the concrete in the first mold. inserting portions of the metal reinforcing structure into the concrete in the second mold. applying a vacuum to'the concrete in the second mold to exhaust' water therefrom until the concrete thereinforms a 'coherent body. discoutinuing the'vacuum treatment of the concrete in the first mold and lifting the same from the body of concrete formed therein, and finally discoutinuing the application of vacuum to 'the concrete in 'the second 'mold and separating the mass of concrete in the second mold from this mold by applying a lifting force to the metal reinforcing structure at points between the two bodies of concrete.

8. The process of making a precast reinforced concrete building panel which comprises placing a mold having a suction surface with said surface in horizontal position. placing a sheet of reinforcing fabric in the mold over said surface pouring concrete into the mold in contact with said fabric, inserting a unitary metal reinforcing structure into the concrete mass with portions of said structure projecting above the surface of the mass, applying a vacuum to the concrete mass through said vacuum surfaceand through the fabric to exhaust water' from the mass and to embed the fabric in a layer of cement drawn to the surface of the mass by the vacuum treatment, placing a second mold having a suction surface with said surface in a horizontal position, pouring a second 'mass of concrete into the second mold, inverting the flrst mold over the second mold while continuing the application of vacuum to the concrete in the first mold. inserting portions of r the metal reinforcing structure into the concrete in the second mold, app y the vacuum to the concrete in the second mold to exhaust water therefrom until the concrete therein forms a coherent body, discontinuing the vacuum treatment of the concrete in the first mold and lifting the same from the' body of concrete formed therein, and then discontinuing the appplication of vacuum to the concrete inthe second mold and separating the mass of concrete in the second mold from this mold.` i

lapcmo 9. The process ot making a prec-.ast reln'toreed concrete building panelwhich comprises placing a mold having a suction surface with said surface in a horizontal position, piacing e sheet of reinforcing iabric in the mold over said surface, pouring concrete into the mold in contact with said fabric, inserting a unltary metal reinforcin structure into the concrete mass with portio'ns of said structureptojecting above the surface of the mass, applying a vacuum--to the concrete mass through said vacuum surface and through-the tabric to exhaust water trom' the mass and to embed the fabric in s, layer of cement drawn to the. surface .of the mass by the vacuun treatment. placing a second mold having a suction surface with said surface in a horizontal position.

placing a sheet of reintorclng tabric in the secod mold over the suction surface thereot. pouring a second mass of concrete into the second mold invertig the first mold over the second mold while continulng the application of 'vecuum to the concrete in the first mold, b-lnging the molds close together until portions o! the metal reinorcing structure are inserted in the 10-' concrete mass in the second mold, applying a vacuum to the concrete in the second mold to exhaust water therefrom until the concrete thereintoris a coherent body, discontinuing the vacuum treatment o!- concrete in the first mold and liiting the same from the concrete body iorxned thei-ein, and finally discontinuing the application ot vacuum to the concrete in the second mold and separating the finished panel !rom the second mold.

BURN& ROENSCH. PAUL-BROWN.

cited in the file c! this patent UNITED STATES PATENTS Number Name Date 640.653 Guy Jan. 2, 1900 &116.557 Biilner May 10, 1938 &175.715 Denning Oct. 10, 1939 2295320 *Moore Sept. 8, 1942 '2305584 :F oater Dec. 22. 1942 !310.400 Crane et al. Feb. 9, 1943 &421.584 Terry June 3, 1947 

